Algebraic Attacks on the Courtois Toy Cipher

Abstract

This article presents and discusses some of the most important algebraic attack algorithms (F ₄, DR, XL) and employs them against Courtois' toy cipher (CTC). Also, CTC is attacked using more specialized algorithms and the experimental results of these attacks are presented.     

Simple analytical method to calculate the radial energy deposition profile in an isotropic diode-pumped solid-state laser rod

We provide an approximate but simple analytical solution to the radial distribution of deposited energy in a diode-array-pumped laser rod, subject to some assumptions that are naturally fulfilled for most applications of practical interest. The solution is useful to survey quickly irradiance distributions for a wide variety of pumping geometries and to find the radially most uniform energy deposition. We find that the radial deposition profile, as well as the pump light absorption efficiency, is largely controlled by just two dimensionless parameters: the number of absorption depths and the ratio of the width of the unabsorbed pump beam at the rod center divided by the rod radius. A side-by-side comparison with a numerical model is given. Results describing the best achievable trade-off between absorption efficiency and pumping uniformity are presented in the form of a recipe that can be followed without studying our research in detail. Finally, the model equations are applied to a practical side-pumped geometry.     

Possible correlation effects of surface state electrons on a solid hydrogen film

We have investigated the transport properties of surface state electrons on thin quench-condensed hydrogen films for various electron densities. The surface state electron mobility showed a continuous dependence on the plasma parameter in the range from 20 to 130, indicating a strong influence of correlation effects within the electron system for all measured values of .     

Multichannel Raman gas analyzer: the data acquisition and control system. Measurement improvement with blue laser light

In this paper, the data acquisition and control system of a multichannel Raman effect-based gas analysis device is presented, together with the improvements achieved in measurement of gas concentration sensitivities as a result of the operation of the system with a new blue laser-light source. The multichannel Raman gas sensor (MRGS) is based on the linear Raman scattering effect and uses photo multiplier tubes (PMTs) in the photon-counting mode of operation. An embedded microcontroller-based data acquisition and control (MDAC) system collects, digitizes, processes, and stores in real time the data from six photon-counting modules and the accompanying sensors, along with an overall system control through appropriate actuators. Recent advances in the development of solid-state laser sources have enabled the use of a new, state-of-the-art, blue laser for the excitation of the Raman effect. Using this blue laser source, improvements in the sensitivities in measurements of concentration for all tested gases (SO/sub 2/, CO/sub 2/, CO, NO/sub 2/, C/sub 6/H/sub 6/, and N/sub 2/) have been substantiated, compared with the green laser source previously used and reported in a related article.     

Coexistence of Low Damping and Strong Magnetoelastic Coupling in Epitaxial Spinel Ferrite Thin Films

Low‐loss magnetization dynamics and strong magnetoelastic coupling are generally mutually exclusive properties due to opposing dependencies on spin–orbit interactions. So far, the lack of low‐damping, magnetostrictive ferrite films has hindered the development of power‐efficient magnetoelectric and acoustic spintronic devices. Here, magnetically soft epitaxial spinel NiZnAl‐ferrite thin films with an unusually low Gilbert damping parameter (<3 × 10^?3), as well as strong magnetoelastic coupling evidenced by a giant strain‐induced anisotropy field (≈1 T) and a sizable magnetostriction coefficient (≈10 ppm), are reported. This exceptional combination of low intrinsic damping and substantial magnetostriction arises from the cation chemistry of NiZnAl‐ferrite. At the same time, the coherently strained film structure suppresses extrinsic damping, enables soft magnetic behavior, and generates large easy‐plane magnetoelastic anisotropy. These findings provide a foundation for a new class of low‐loss, magnetoelastic thin film materials that are promising for spin‐mechanical devices.     

A Comparison of Methods for Determining the Wattage Output and Energy Distribution in Microwave Ovens

Two characteristics of microwave ovens that are important to consumers as they select and use microwave ovens are the wattage output (cooking power) and the evenness of distribution of energy within the oven cavity. Several test methods have been proposed to measure each of these characteristics, but there is not agreement in the industry on realistic methods of their measurement. The purpose of this study is to evaluate a variety of methods for determining cooking power and energy distribution. Cooking power was measured using the temperature rise of water loads. The influence of initial load temperature, quantity of water, profile, and location of the load within the cavity (centrally located versus dispersed) was determined. Energy distribution was measured using nonfood loads (a three-dimensional copying paper load and various water loads), a simple food (gelatin), and a complex food (custard). Placement of the load, the profile, and the composition of the load affected the apparent energy distribution. Recommendations for standardized tests resulted from this research.     

Cellular memory: neutrophil orientation reverses during temporally decreasing chemoattractant concentrations

Cell directional orientation or shape polarization is the first cellular step in neutrophil locomotion. To better understand how chemoattractants interact with cells, we studied neutrophil polarization (or shape changes) during exposure to a temporally decreasing chemoattractant signal of N-formyl-methionyl-leucyl-phenylalanine (FMLP) in the absence of a spatial concentration gradient. To accomplish this objective, we used a manifold of differing FMLP concentrations attached to a stopped-flow microscope chamber. Spatial gradients of a fluorescent chemotactic peptide could not be detected in the chamber by using microfluorometry. When FMLP was injected at continually increasing concentrations at 10-s intervals, the shape and relative direction of the neutrophil persisted. However, when temporally decreasing FMLP concentrations were injected, approximately 80% of the cells changed their direction with 44% of the total cells swinging about to 180 degrees +/- 15 degrees. Most of these directional changes involved dissolution of both the lamellipodium and uropod and reformation of these structures 180 degrees from their original positions. This research suggests that neutrophils reverse their morphological polarity when exposed to temporally decreasing ligand concentrations by "remembering" their ligand exposure history and relative direction.     

Functionality of MDCK kidney tubular cells on flat polymer membranes for biohybrid kidney

The prerequisite for the development of a biohybrid artificial kidney, is a substrate for confluent growth of renal cells forming an epithelial monolayer without any leaks. Conventional cell culture supports cannot be adapted for this purpose, because they lack adequate mechanical properties and thermal stability. From two suitable materials, polysulfone and polyacrylonitrile, two permeable polymeric membranes have been produced that were, according to ISO 10993-5, not cytotoxic. Cloned Madin Darby Canine Kidney (MDCK) cells (an established renal cell line) were cultured on the surface of the plastic materials, and on conventional cell culture supports. With all materials, assays of mitochondrial and lactate dyhydrogenases exhibited similar proliferation and the viability of the MDCK cells. Transmission electron microscopy showed the expression of a normal morphology of kidney tubular cells. Perfect barrier function, consequent on the formation of intercellular junctions in a confluent tight epithelium, was visualized in electron micrographs, and quantified by measurement of the transepithelial resistance. The uniformity of the cells grown was demonstrated in samples by electron microscopy and in the whole epithelium by intravital impedance analysis. It was concluded that polymeric membranes produced from polysulfone or polyacrylonitrile are appropriate substrates in the design of biohybrid kidney devices. © 1998 Kluwer Academic Publishers